I really enjoy the Calgary Exhibition and Stampede grounds.
The Stampede is the biggest event that is held on these grounds every year for 10 long and wonderful days where the city is shut down. However, throughout the year this space is used for many other things such as event including: Octoberfest, Calgary Home and Garden Show, Calgary Flames Games, Calgary Hitmen Games, Calgary Roughneck Games, etc.
Parking can be a little expensive on these grounds, which I understand some people complain about, however it is because the city wants to encourage people to take the train to be environmentally friendly.
The city and stampede is great at keeping the area clean and after the 10 days it looks as though Stampede was never there :)